Authorities say Ciancia was determined to lash out at the TSA, saying in a note he wanted to kill at least one of its officers.

It's not clear why he targeted the agency, but a note found in his duffel bag suggested the 23-year-old unemployed motorcycle mechanic was willing to kill almost any airport security officer he could confront with his AR-15 semi-automatic rifle.

``Black, white, yellow, brown, I don't discriminate,'' the note read, according to a law enforcement official briefed on the investigation but speaking on condition of anonymity.

The note also mentioned "fiat currency'' and ``NWO,'' possible references to the New World Order, a conspiracy theory that foresees a totalitarian one-world government.

Ciancia had moved to LA from New Jersey where on Friday his father called police, worried about his son after he sent texts to his family suggesting he might be in trouble or even harm himself, at one point even saying goodbye.

New Jersey police called LA police who sent a patrol car to Ciancia's apartment. There, two roommates said they had seen him a day earlier and he appeared to be fine.

By that time, gunfire was already breaking out at the airport, prompting passengers to drop to the floor or run for their lives.

Ciancia had walked into the airport, pulled the rifle from his bag and began firing at TSA officers.

Travelers are screened by TSA agents after Terminal 3 was re-opened a day after the shooting.Source: AFP

Leon Saryan of Milwaukee said he was cowering in a corner when the shooter approached.

"He looked at me and asked, 'TSA?' I shook my head no, and he continued on down toward the gate. He had his gun at the ready and, but for the grace of God, I am here to tell about it,'' Saryan said.

Airport officials said Terminal 3 was open again as of early Saturday afternoon after a prolonged shutdown that was particularly troublesome for those hoping to head to the East Coast or across the Pacific Ocean, including hundreds of Australians and New Zealanders.

About 1550 flights with 167,000 passengers were affected, airport spokeswoman Nancy Castles said in a statement on Saturday.

A NOTE ABOUT RELEVANT ADVERTISING: We collect information about the content (including ads) you use across this site and use it to make both advertising and content more relevant to you on our network and other sites.